Contact lenses comprising lipophilised cyclodextrins

ABSTRACT

A process for producing a contact lens and a contact lens comprising a crosslinked lipophilised cyclodextrin derivative, wherein each repeating cyclodextrin unit includes at least one polysiloxane group. The process for producing the contact lens includes the reaction of a cyclodextrin with a polysiloxane.

The present invention relates to contact lenses comprising speciallymodified cyclodextrins, to the manufacture of those contact lenses andto the use of the specially modified cyclodextrins in the manufacture ofcontact lenses.

Cyclodextrins are known. They are naturally occurring cycloamyloses.Known in particular are α-cyclodextrin, which consists of six units,β-cyclodextrin, which consists of seven units, and γ-cyclodextrin, whichconsists of eight units. Unit in this context in each case denotes aring of formula A ##STR1##

Six, seven or eight rings of formula A, as the case may be, form aclosed cycle having α-(1-4)-bonded glucopyranose units, depending onwhether the cyclodextrin is α-cyclodextrin, which contains six rings offormula A,β-cyclodextrin, which contains seven rings of formula A, orγ-cyclodextrin, which contains 8 rings of formula A. Each cyclodextrinmolecule is thus a macromolecule with a cavity. Cyclodextrins containingmore than 8 units of formula A are also known. They are usually obtainedin the form of mixtures which can, if necessary, be separated.

The cyclodextrins used in accordance with the invention are so modifiedthat they no longer contain exclusively free hydroxy groups. Instead,some or all of the hydroxy groups are etherified. In addition some, butat least one, of the etherified groups are functionalised such that theycan be reacted with hydrogen-polysiloxanes, for example withα,ω-di-hydrogen-polysiloxanes. That reaction results not only in afurther functionalisation of an individual cyclodextrin molecule but,owing to the multi- or bi-functionality for example of theα,ω-dihydrogen-polysiloxanes, in the crosslinking of differentcyclodextrin molecules with one another. It is by that means possible toproduce a material comprising polymeric cyclodextrin which, inter aliaas a result of the presence of siloxane bridges, has more or lessstrongly pronounced lipophilic properties.

That material has surprisingly proved extraordinarily suitable for themanufacture of contact lenses. For example it is possible to adjust thehydrophilic and lipophilic properties of the material by varying thechain length of the siloxane bridges. In addition there are furtherparameters that permit optimisation of the properties desired for thepurpose in question. Those include the nature and number of the ethergroups. The contact lenses obtainable from the said material arecolourless, transparent, have a good mechanical stability and meet thehigh requirements made of contact lenses, for example also in respect oftheir contact angle. The contact lenses according to the invention areparticularly attractive, however, in view of their oxygen permeability(Dk). In most cases the Dk values are approximately from 100 to 200 witha maximum value of up to 500.

The present invention therefore relates to a contact lens comprising acrosslinked lipophilised cyclodextrin derivative which is obtainable byreacting a compound of formula I ##STR2## with a compound of formula II##STR3## in which formulae

n is an integer of from 6 to 15,

the radicals R¹ are each, independently of the others, hydrogen, R² orR³ wherein, of the (3 times n) radicals R¹, at least one radical R¹ hasthe meaning of R³ and the remaining radicals R¹ are hydrogen or have themeaning of R²,

R² being unsubstituted or halogen-substituted alkyl or alkyl-substitutedaryl and

R³ being unsubstituted or halogen-substituted alkenyl,

x is an integer of from 1 to 10 000, and

R⁴, R⁵ and R⁶ are each, independently of the others, hydrogen, alkyl,phenyl or hydroxy, with the proviso that at least two of the radicalsR⁴, R⁵ and R⁶ in a compound of formula II are hydrogen.

Preferably, a maximum of about 50% of the radicals R⁴, R⁵ and R⁶ in acompound of formula II are hydrogen.

Radicals and groups designated "lower", such as lower alkyl, loweralkenyl etc., denote radicals and groups having up to 7 carbon atoms,preferably up to 4 carbon atoms. Radicals such as alkyl, alkenyl,alkylene or the like are unbranched or branched radicals of that kind.

Alkyl is especially unbranched or branched alkyl having up to 12 carbonatoms, preferably lower alkyl, and is e.g. methyl, ethyl, propyl,2-propyl, butyl, tert-butyl, pentyl, hexyl, octyl or decyl.

Halogen is fluorine, chlorine or bromine, but may also be iodine and,according to the invention, is preferably fluorine.

Aryl is especially an aromatic hydrocarbon radical and is preferablynaphthyl or phenyl.

Alkenyl is especially unbranched or branched alkenyl having up to 12carbon atoms, preferably lower alkenyl, and is e.g. ethenyl, propenyl,butenyl, pentenyl, hexenyl, octenyl or decenyl. Alkenyl may also be apolyunsaturated radical, that is e.g. lower alk-dien-yl, such ashexadienyl or pentadienyl, e.g. hexa-2,5-dien-1-yl. The carbon-carbondouble bond present in the alkenyl radicals may be located in a terminalposition or in the chain. In the case of polyunsaturated radicals atleast one carbon-carbon double bond may be in a terminal position.

Halogen-substituted alkyl is especially fluorine-substituted alkyl, suchas fluoro-lower alkyl, e.g. trifluoromethyl, trifiuoroethyl,pentafluoroethyl, heptafluorobutyl or nonafluorobutyl.

Alkyl-substituted aryl is especially phenyl mono- to tri-substituted bylower alkyl, such as, e.g., tolyl, ethylphenyl, xylyl, butylphenyl orpentylphenyl.

Halogen-substituted alkenyl is especially fluorine-substituted alkenyl,such as fluoro-lower alkenyl, e.g. trifluoroethenyl,pentafluoropropenyl, heptafluorobutenyl or nonafluorohexenyl.Halogen-substituted alkenyl may also have one or more carbon-carbondouble bonds and that bond may be located in a terminal position or inthe chain. In the case of polyunsaturated radicals at least onecarbon-carbon double bond may be in a terminal position.

The index n represents an integer of from 6 to 15, especially an integerof from 6 to 10, and is preferably the integer 6, 7 or 8. The index n isespecially the integer 7, that is to say the cyclodextrins used areprepared from β-cyclodextrin. It is also possible to use mixtures ofcyclodextrins having different numbers of α-(1-4)-bonded glucopyranoseunits, that is to say the index n in a polymeric cyclodextrin used inaccordance with the invention for contact lenses may have differentvalues ranging from 6 to 15.

R¹ is preferably R² or R³. Of the (3 times n) radicals R¹ (e.g. the 18radicals R¹ in the case where n is 6, the 21 radicals R¹ in the casewhere n is 7 or the 24 radicals R¹ in the case where n is 8), preferablyfrom 50% to 100% of a third of those radicals have the meaning of R³,whilst the other radicals R¹ have the meaning of R². The radicals R³present are generally uniformly distributed in the rings of formula I.They are furthermore preferably in the 3-position. For the purpose ofillustration, an α-cyclodextrin type in which 100% of a third of theradicals R¹, uniformly in the 3-position, have the meaning of R³, whilst100% of the other two thirds of the radicals R¹ have the meaning of R²is reproduced in the following as formula IA: ##STR4##

On the other hand, an α-cyclodextrin type in which only 50% of a thirdof the radicals R¹ have the meaning of R³ would be represented by aformula corresponding to formula IA in which, of course, not all of the6 rings of the cyclodextrin would have a radical R³ but only every otherring, whilst all of the other radicals R¹, in this case 15 radicals R¹,would have the meaning of R².

Especially preferably, 100% of a third of the radicals R¹, uniformlydistributed in the rings of formula I, have the meaning of R³, whilstthe other two thirds of the radicals R¹ have the meaning of R².Particularly preferably, the radicals R³ are uniformly located in the3-position. That arrangement, an example of the case in which the indexn is six, is reproduced in formula IA.

The radicals R² are preferably alkyl, especially lower alkyl and, moreespecially, lower alkyl having from 4 to 7 carbon atoms, such as butyl,pentyl or hexyl.

The radicals R³ are preferably alkenyl, especially lower alkenyl and,more especially, lower alkenyl having from 3 to 6 carbon atoms, such asallyl, pentenyl or hexenyl.

The index x is from 1 to 10 000, preferably from 1 to 1000, especiallyfrom 1 to 500, more especially from 1 to 200 or from 1 to 100 and evenmore especially from 2 to 85.

In connection with the radicals R⁴, R⁵ and R⁶, at least two, butpreferably not more than about 50% of all of the radicals R⁴, R⁵ and R⁶,must be hydrogen. It is especially preferred for not more than about 25%of all radicals R⁴, R⁵ and R⁶ to be hydrogen. Particularly preferablyprecisely two of the radicals R⁴, R⁵ and R⁶ are hydrogen. Those radicalsare preferably the two R⁶ radicals.

A preferred combination of meanings in which two silicon-hydrogen bondsare located in terminal positions is as follows:

The radicals R⁴ and R⁵ are preferably alkyl or phenyl, especially loweralkyl, such as methyl or ethyl, or phenyl. An especially preferredmeaning of the radicals R⁴ and R⁵ is lower alkyl having up to 4 carbonatoms, such as methyl. The radicals R⁶ are hydrogen. Compounds offormula II in which the radicals R⁴, R⁵ and R⁶ have those meanings areα,ω-dihydrogen-polysiloxanes.

Another preferred combination of meanings in which the silicon-hydrogenbonds are not necessarily located in terminal positions is as follows:

The radicals R⁴, R⁵ and R⁶ are hydrogen, alkyl or phenyl, especiallyhydrogen, lower alkyl, such as methyl or ethyl, or phenyl, with theproviso that at least two of the radicals R⁴, R⁵ and R⁶, and preferablya maximum of 50% of the radicals R⁴, R⁵ and R⁶, are hydrogen.

The present invention therefore relates especially to a contact lenscomprising a crosslinked lipophilised cyclodextrin derivative which isobtainable by reacting a compound of formula I with a compound offormula II, in which formulae

n is an integer of from 6 to 15,

the radicals R¹ are each, independently of the others, hydrogen, R² orR³ wherein, of the (3 times n) radicals R¹, at least one radical R¹ hasthe meaning of R³ and the remaining radicals R¹ are hydrogen or have themeaning of R²,

R² being unsubstituted alkyl and

R³ being unsubstituted alkenyl,

x is an integer of from 1 to 1000, and

R⁴, R⁵ and R⁶ are each, independently of the others, hydrogen, alkyl orphenyl, at least two of the radicals R⁴, R⁵ and R⁶ being hydrogen.

Preferred among those is a contact lens comprising a crosslinkedlipophilised cyclodextrin derivative which is obtainable by reacting acompound of formula I with a compound of formula II, in which formulae nis an integer of from 6 to 15, the radicals R¹ in the 2-position and inthe 6-position are unsubstituted alkyl and the radicals R¹ in the3-position are unsubstituted alkenyl, x is an integer of from 1 to 1000and R⁴, R⁵ and R⁶ are each, independently of the others, hydrogen, alkylor phenyl, at least two of the radicals R⁴, R⁵ and R⁶ being hydrogen.

Also preferred among those is a contact lens comprising a crosslinkedlipophilised cyclodextrin derivative which is obtainable by reacting acompound of formula I with a compound of formula 11, in which formulae nis an integer of from 6 to 15, the radicals R¹ in the 2-position and inthe 6-position are unsubstituted alkyl, and at least 50% of the radicalsR¹ in the 3-position are unsubstituted alkenyl whilst the remainingpercentage of the radicals R¹ in the 3-position are unsubstituted alkyl,x is an integer of from 1 to 1000 and R⁴, R⁵ and R⁶ are each,independently of the others, hydrogen, alkyl or phenyl, at least two ofthe radicals R⁴, R⁵ and R⁶ being hydrogen.

Furthermore preferred among those is a contact lens comprising acrosslinked lipophilised cyclodextrin derivative which is obtainable byreacting a compound of formula I with a compound of formula H, in whichformulae n is an integer of from 6 to 15, the radicals R¹ in the2-position and in the 6-position are unsubstituted alkenyl and theradicals R¹ in the 3-position are hydrogen, x is an integer of from 1 to1000 and R⁴, R⁵ and R⁶ are each, independently of the others, hydrogen,alkyl or phenyl, at least two of the radicals R⁴, R⁵ and R⁶ beinghydrogen.

The present invention relates especially preferably to a contact lenscomprising a crosslinked lipophilised cyclodextrin derivative which isobtainable by reacting a compound of formula I with a compound offormula II, in which formulae n is an integer of from 6 to 15, theradicals R¹ are each, independently of the others, hydrogen, R² or R³wherein, of the (3 times n) radicals R¹, from 50% to 100% of a third ofthose radicals have the meaning of R³ whilst the other radicals R¹ arehydrogen or have the meaning of R², R² being unsubstituted alkyl and R³being unsubstituted alkenyl, x is an integer of from 1 to 500 and R⁴, R⁵and R⁶ are each, independently of the others, hydrogen, alkyl or phenyl,at least two of the radicals R⁴, R⁵ and R⁶ being hydrogen.

The present invention therefore relates most especially to a contactlens comprising a crosslinked lipophilised cyclodextrin derivative whichis obtainable by reacting a compound of formula III ##STR5## in whichformulae

n is an integer of from 6 to 15,

R² is unsubstituted alkyl,

R³ is unsubstituted alkenyl,

x is an integer of from 1 to 500 and

R⁴ and R⁵ are each, independently of the other, alkyl or phenyl.

The index n in a compound of formula III is preferably 6, 7 or 8.

Equally, the present invention relates also to a contact lens comprisinga crosslinked lipophilised cyclodextrin derivative which is obtainableby reacting a compound of formula III as defined above with a compoundof formula II in which x is an integer of from 1 to 500 and the radicalsR⁴, R⁵ and R⁶ are hydrogen, alkyl or phenyl, with the proviso that aminimum of two of the radicals R⁴, R⁵ and R⁶, and a maximum of about 25%of the radicals R⁴, R⁵ and R⁶, are hydrogen.

The present invention relates especially to a contact lens comprising acrosslinked lipophilised cyclodextrin derivative which is obtainable byreacting a compound of formula III with a compound of formula IV, inwhich formulae

n is an integer 6, 7 or 8,

R² is lower alkyl having from 4 to 7 carbon atoms,

R³ is lower alkenyl having from 3 to 6 carbon atoms,

x is an integer of from 1 to 200 and

R⁴ and R⁵ are each, independently of the other, lower alkyl or phenyl.

The present invention relates also to a contact lens comprising acrosslinked lipophilised cyclodextrin derivative which has repeatingsub-units of formula V ##STR6## in which

n is an integer of from 6 to 15,

the radicals R¹ are each, independently of the others, hydrogen, R² orR⁷, wherein, of the (3 times n) radicals R¹, at least one radical R¹ hasthe meaning of R⁷ and the remaining radicals R¹ are hydrogen or have themeaning of R²,

R² being unsubstituted or halogen-substituted alkyl or alkyl-substitutedaryl and

R⁷ being a di- or poly-valent radical of formula VI ##STR7## in which

x is an integer of from 1 to 10 000, and

R⁴, R⁵ and R⁸ are each, independently of the others, hydrogen, alkyl,unsubstituted or halogen-substituted alkylene or alkenylene, phenyl orhydroxy, with the proviso that at least two of the radicals R⁴, R⁵ andR⁸ in a radical of formula VI are unsubstituted or halogen-substitutedalkylene or alkenylene.

Preferably a maximum of about 50% of the radicals R⁴, R⁵ and R⁸ in aradical of formula VI are hydrogen. The valency of the radical offormula VI depends on the number of substituents R⁴, R⁵ and R⁸ that areunsubstituted or halogen-substituted alkylene or alkenylene. The radicalof formula VI is at least divalent, preferably di- to penta-valent, andespecially preferably divalent.

Alkylene is especially unbranched or branched alkylene having up to 12carbon atoms, preferably lower alkylene, and is e.g. ethylene,propylene, butylene, pentylene, hexylene, octylene or decylene.

Alkenylene is especially unbranched or branched alkenylene having up to12 carbon atoms, preferably lower alkenylene, and is e.g. butenylene,pentenylene, hexenylene, octenylene or decenylene.

Halogen-substituted alkylene is especially fluorine-substitutedalkylene, such as fluoro-lower alkylene, e.g. difluoroethylene,tetrafluoroethylene, hexafluorobutylene or octafluorobutylene.

Halogen-substituted alkenylene is especially fluorine-substitutedalkenylene, such as fluoro-lower alkenylene, e.g. hexafluorobutenyleneor octafluorohexenylene. A carbon-carbon double bond present in thealkenylene radicals or in the halogen-substituted alkenylene radicalsmay be located in a terminal position or in the chain.

The index n is an integer of from 6 to 15, especially an integer of from6 to 10, and preferably the integer 6, 7 or 8. The index n is especiallythe integer 7, that is to say the cyclodextrins used are prepared fromβ-cyclodextrin. It is also possible to use mixtures of cyclodextrinshaving different numbers of α-(1-4)-bonded glucopyranose units, that isto say the index n in a polymeric cyclodextrin used in accordance withthe invention for contact lenses can have different values ranging from6 to 15.

R¹ is preferably R² or R⁷. Of the (3 times n) radicals R¹ (e.g. the 18radicals R¹ in the case where n is 6, the 21 radicals R¹ in the casewhere n is 7 or the 24 radicals R¹ in the case where n is 8), preferablyfrom 50% to 100% of a third of those radicals have the meaning of R⁷,whilst the other radicals R¹ have the meaning of R². The radicals R⁷present are usually uniformly distributed in the rings of formula V. Inaddition they are preferably located in the 3-position. For the purposeof illustration an α-cyclodextrin type in which 100% of a third of theradicals R¹, uniformly in the 3-position, have the meaning of R⁷, whilst100% of the other two thirds of the radicals R¹ have the meaning of R²is shown in the following as formula VA: ##STR8##

On the other hand, an α-cyclodextrin type in which only 50% of a thirdof the radicals R¹ have the meaning of R⁷ would be represented by aformula corresponding to formula VA in which, of course, not all of the6 rings of the cyclodextrin would have a radical R⁷ but only every otherring, whilst all of the other radicals R¹, in this case 15 radicals R¹,would have the meaning of R².

Especially preferably 100% of a third of the radicals R¹, uniformlydistributed in the rings of formula I, have the meaning of R⁷, whilstthe other two thirds of the radicals R¹ have the meaning of R².Particularly preferably, the radicals R⁷ are located uniformly in the3-position. That arrangement, an example of the case in which the indexn is six, is reproduced in formula VA.

The radicals R² are preferably alkyl, especially lower alkyl and, moreespecially, lower alkyl having from 4 to 7 carbon atoms, such as butyl,pentyl or hexyl.

The radicals R⁴, R⁵ and R⁸ are preferably alkylene, especially loweralkylene and, more especially, lower alkylene having from 3 to 6 carbonatoms, such as 1,3-propylene, 1,2-propylene, 1,5-pentylene or1,6-hexylene.

The index x is from 1 to 10 000, preferably from 1 to 1000, especiallyfrom 1 to 500, more especially from 1 to 200 or from 1 to 100, and evenmore especially from 2 to 85.

In connection with the sub-units of formula V, at least two of theradicals R⁴, R⁵ and R⁸ must be unsubstituted or halogen-substitutedalkylene or alkenylene. Also, preferably not more than about 50% of allradicals R⁴, R⁵ and R⁸ are hydrogen. Especially preferably, not morethan about 25% of all radicals R⁴, R⁵ and R⁸ are hydrogen. Particularlypreferably, none of the radicals R⁴, R⁵ and R⁸ is hydrogen. Alsoparticularly preferably, precisely two of the radicals R⁴, R⁵ and R⁸ areunsubstituted or halogen-substituted alkylene or alkenylene. Thoseradicals are preferably the two R⁸ radicals.

A preferred combination of meanings for the sub-units of formula V is asfollows:

The radicals R⁴ and R⁵ are preferably alkyl or phenyl, especially loweralkyl, such as methyl or ethyl, or phenyl. An especially preferredmeaning of the radicals R⁴ and R⁵ is lower alkyl having up to 4 carbonatoms, such as methyl. The radicals R⁸ are alkylene, especially loweralkylene. Radicals of formula VI in which the radicals R⁴, R⁵ and R⁸have those meanings are derived from α,ω-dihydrogen-polysiloxanes.

Another preferred combination of meanings for the sub-units of formula Vis as follows:

The radicals R⁴, R⁵ and R⁸ are hydrogen, alkyl, alkylene or phenyl,especially hydrogen, lower alkyl, such as methyl or ethyl, loweralkylene, such as pentylene, or phenyl, with the proviso that a minimumof two of the radicals R⁴, R⁵ and R⁸ are alkylene, especially loweralkylene, and preferably a maximum of 50% of the radicals R⁴, R⁵ and R⁸are hydrogen.

The present invention therefore relates especially to a contact lenscomprising a crosslinked lipophilised cyclodextrin derivative which hasrepeating sub-units of formula V in which

n is an integer of from 6 to 15,

the radicals R¹ are each, independently of the others, hydrogen, R² orR⁷ wherein, of the (3 times n) radicals R¹, at least one radical R¹ hasthe meaning of R⁷ and the remaining radicals R¹ are hydrogen or have themeaning of R²,

R² being unsubstituted alkyl and

R⁷ being a di- or poly-valent radical of formula VI in which

x is an integer of from 1 to 1000 and

R⁴, R⁵ and R⁸ are each, independently of the others, hydrogen, alkyl,alkylene or phenyl, at least two of the radicals R⁴, R⁵ and R⁸ beingalkylene.

Preferred among those is a contact lens comprising a crosslinkedlipophilised cyclodextrin derivative which has repeating sub-units offormula V in which n is an integer of from 6 to 15, the radicals R¹ inthe 2-position and in the 6-position are unsubstituted alkyl, theradicals R¹ in the 3-position have the meaning of R⁷, x is an integer offrom 1 to 1000 and R⁴, R⁵ and R⁸ are each, independently of the others,hydrogen, alkyl, alkylene or phenyl, at least two of the radicals R⁴, R⁵and R⁸ being alkylene.

Also preferred among those is a contact lens comprising a crosslinkedlipophilised cyclodextrin derivative which has repeating sub-units offormula V in which n is an integer of from 6 to 15, the radicals R¹ inthe 2-position and in the 6-position are unsubstituted alkyl, and atleast 50% of the radicals R¹ in the 3-position have the meaning of R⁷whilst the remaining percentage of the radicals R¹ in the 3-position areunsubstituted alkyl, x is an integer of from 1 to 1000 and R⁴, R⁵ and R⁸are each, independently of the others, hydrogen, alkyl, alkylene orphenyl, at least two of the radicals R⁴, R⁵ and R⁸ being alkylene.

Furthermore preferred among those is a contact lens comprising acrosslinked lipophilised cyclodextrin derivative which has repeatingsub-units of formula V in which n is an integer of from 6 to 15, theradicals R¹ in the 3-position are hydrogen, the radicals R¹ in the2-position and in the 6-position have the meaning of R⁷, x is an integerof from 1 to 1000 and R⁴, R⁵ and R⁸ are each, independently of theothers, hydrogen, alkyl, alkylene or phenyl, at least two of theradicals R⁴, R⁵ and R⁸ being alkylene.

The present invention relates especially preferably to a contact lenscomprising a crosslinked lipophilised cyclodextrin derivative which hasrepeating sub-units of formula V in which

n is an integer of from 6 to 15,

the radicals R¹ are each, independently of the others, hydrogen, R² orR⁷ wherein, of the (3 times n) radicals R¹, from 50% to 100% of a thirdof those radicals have the meaning of R⁷ whilst the other radicals R¹are hydrogen or have the meaning of R²,

R² being unsubstituted alkyl and

R⁷ being a di- or poly-valent radical of formula VI in which

x is an integer of from 1 to 500 and

R⁴, R⁵ and R⁸ are each, independently of the others, hydrogen, alkyl,alkylene or phenyl, at least two of the radicals R⁴, R⁵ and R⁸ beingalkylene.

The present invention therefore relates most especially to a contactlens comprising a crosslinked lipophilised cyclodextrin derivative whichhas repeating sub-units of formula VII ##STR9## wherein

n is an integer of from 6 to 15,

R² is unsubstituted alkyl, and

R⁷ is a divalent radical of formula VIII ##STR10## wherein

x is an integer of from 1 to 500,

R⁴ and R⁵ are each, independently of the other, alkyl or phenyl, and

R⁸ is alkylene.

The index n in a compound of formula VII is preferably 6, 7 or 8.

Equally, the present invention relates also to a contact lens comprisinga crosslinked lipophilised cyclodextrin derivative which has repeatingsub-units of formula VII as defined above, wherein R⁷ is a di- orpoly-valent radical of formula VI as defined above in which x is aninteger of from 1 to 500, and the radicals R⁴, R⁵ and R⁸ are hydrogen,alkyl, alkylene or phenyl, with the proviso that a minimum of two of theradicals R⁴, R⁵ and R⁸ are alkylene and a maximum of about 25% of theradicals R⁴, R⁵ and R⁸ are hydrogen.

The present invention relates especially to a contact lens comprising acrosslinked lipophilised cyclodextrin derivative which has repeatingsub-units of formula VII wherein R⁷ is a divalent radical of formulaVII, in which formulae n is an integer 6, 7 or 8, R² is lower alkylhaving from 4 to 7 carbon atoms, x is an integer of from 1 to 200, R⁴and R⁵ are each, independently of the other, lower alkyl or phenyl, andR⁸ is lower alkylene having from 3 to 6 carbon atoms.

The cyclodextrins of which a partial formula is shown in formula A arecommercially available as are also the hydrogen-polysiloxanes offormulae II and IV. The compounds of formulae II and IV that are notcommercially available can be prepared in a manner known per se.

The crosslinked lipophilised cyclodextrin derivatives from which thecontact lenses according to the invention can be produced can beobtained, for example, as follows:

The radicals R² and R³ are introduced into a cyclodextrin in anappropriate manner by alk(en)ylation. This can be effectedsimultaneously with a mixture of an alkylation agent and an alkenylationagent, or sequentially with an alkylation agent and with an alkenylationagent. For example, a cyclodextrin can first of all be converted into acompound of formula I wherein two thirds of the radicals R¹ are alkyland the remaining third of the radicals R¹ are hydrogen. The conversionof the radicals R¹ representing hydrogen into radicals R³ can then becarried out by reaction with an alkenylation agent.

Alternatively, a cyclodextrin can first of all be converted into acompound of formula I wherein two thirds of the radicals R¹ are alkyland the remaining third of the radicals R¹ are hydrogen. The conversionof the radicals R¹ representing hydrogen into radicals R² or R³ can thenbe carried out by reaction with a mixture of an alkylation agent and analkenylation agent.

Alkylation agents and alkenylation agents are reactive esters of thealkyl and alkenyl compounds respectively, e.g. sulfonic acid esters orhydrohalic acid esters, such as alkyl and alkenyl sulfonates orbromides, especially e.g. lower alkyl bromides such as 1-bromo-n-pentaneor 1-bromo-n-pentene.

The alkylation or alkenylation is carried out under conditions typicalfor that purpose that are familiar to the person skilled in the art, forexample in an inert solvent, such as an ether, e.g. tetrahydrofuran, ata temperature of from 0° C. to the boiling temperature of the solventused and, where appropriate, under inert gas, such as a nitrogenatmosphere.

As a result a cyclodextrin derivative is obtained thus which comprisesat least one carbon-carbon double bond per macromolecule, preferably 6,7 or 8 such double bonds per macromolecule, that is to say as many suchdouble bonds as correspond to the preferred meaning of the index n informula I.

The cyclodextrin derivatives of formula I so obtained are then reactedwith a compound of formula II. For that purpose either approximatelyequimolar amounts are used, based on the number of carbon-carbon doublebonds in the compounds of formula I and the number of silicon-hydrogenbonds in compounds of formula II, or a molar excess of one or the othercomponent is used. In that reaction in each case an Si--H bond can beadded to a C--C double bond and in that manner the cyclodextrinderivatives of formula I are crosslinked with one another by way ofsiloxane bridges.

That reaction also takes place in a manner known per se, e.g. accordingto J. L. Speier, Adv. Organomet. Chem. 17, 407 (1979). There arepreferably used, for example, an inert solvent, such as a hydrocarbon,e.g. toluene, at a temperature of from 0° C. to the boiling temperatureof the solvent used and, where appropriate, inert gas, such as anitrogen atmosphere. The reaction is usually carried out in the presenceof a catalyst. Platinum, platinum compounds or platinum complexes, suchas e.g. cis-bis(styrolo)dichloroplatinum, are especially suitablecatalysts.

The duration of the reaction is from a few minutes up to a few days,e.g. from 2 minutes to 5 days, depending on the circumstances.

The hydrosilylation reaction, which results in polymerisation, may becarried out, for example, on a rotating plate heated to a temperature ofup to about 100° C. In that manner it is possible to obtain films ofdifferent thicknesses which are a lipophilised cyclodextrin/polysiloxanenetwork. That network is the crosslinked lipophilised cyclodextrinderivative, obtainable from the compounds of formulae I and II, fromwhich the contact lenses according to the invention can be produced.

In order to improve the mechanical properties, fillers, for exampleamorphous quartz powder, such as aerosil, for example having a particlesize of from 10 to 100 nm, or titanium dioxide, may be added to thenetworks, and thus also to the contact lenses according to theinvention.

The networks can also be polymerised in another manner known per se, forexample in cylindrical shape, for example by subjecting them in closedcylindrical moulds (tubes) to a temperature programme in which thetemperature is increased in steps from 30° C. to about 100° C. Thetemperature steps may, for example, be of from 5° to 10° C., with aresidence time of from 1 to 12 hours per temperature. 2 or 5-hourperiods are customary, but individual temperatures may also bemaintained for up to 20 hours. Tempering at from 80° to 130° C. isusually carried out for from 1 to 15 hours at the end.

The manufacture of contact lenses of the invention can also be carriedout in a manner known per se. For that purpose e.g. the compounds offormulae I and II are polymerised in cylindrical moulds and, afterreleasing from the moulds, the so-obtainable rods are divided into discsor buttons which can be further processed mechanically, especially byturning processes. In addition, the lenses according to the inventioncan also be manufactured by other processes known per se, such ascasting in static moulds, spin casting, compressing, deep-drawing,thermoforming, turning or laser machining. Those process steps are knownper se and detailed explanation is therefore not required for the personskilled in the art.

The manufacture is carried out preferably, but not necessarily, under aninert atmosphere when using open moulds. If closed moulds are used forthe formation of the polymer, the moulds are advantageously made ofinert materials exhibiting low oxygen permeability and non-adhesiveproperties. Examples of suitable mould materials arepolytetrafluoroethylene, such as Teflon®, silicone rubber, polyethylene,polypropylene and polyesters such as Mylar®. If a suitable mould-releaseagent is employed, moulds made of glass and metal can also be used.

Casting in static moulds may, for example, if moulds having an inner andouter curve are used, give contact lenses directly. Thus contact lensescan be produced directly by polymerisation of the compounds of formulaeI and II in suitable moulds ("full mould" process) or with only onefinished surface ("semi-mould" process).

Spin casting can also be used in accordance with the invention byintroducing a solution of the compounds of formulae I and II into a spincasting mould and then spinning the mould, in the course of which thesolvent evaporates. The finished contact lens, of which the dimensionscan be controlled by the dimensions of the mould, the speed of rotationand the viscosity of the solution introduced, remains in the mould.

Compression is effected in accordance with the invention e.g. bycompression-moulding a sheet of the network. A sheet of the network canbe produced as described above or in a manner known per se by casting asolution of the compounds of formulae I and II.

From a sheet produced e.g. as mentioned above it is possible to producea contact lens, also in a manner known per se, by deep-drawing orthermoforming.

Turning, also, is a possible final process step for the manufacture ofcontact lenses according to the invention. This is used if a blankobtainable e.g. in accordance with one of the processes mentioned aboverequires further machining. The term "turning" is understood to mean themachining down, known per se, of contact lens blanks. Appropriate blankscan be produced, e.g., by the extrusion of round rods and the divisionthereof, or by casting from a solution. The term "contact lens blank" inthis context covers buttons or semi-mould products, such as e.g. blankshaving an inner curve. Typical blanks have thicknesses of 4 or 6 mm anddiameters of from 10 to 17, e.g. 12 or 14, mm.

It is also possible in accordance with the invention to employ lasermachining, using blanks, or using contact lenses produced according toone of the other processes if those lenses require an additional finemachining of their surface.

The following Examples illustrate the subject of the invention withoutlimiting it to the scope of the Examples. Percentage Figures arepercentages by weight unless expressly specified otherwise. Temperaturesare in degrees Celsius.

Contact angles are determined in accordance with the followingprocedure: The contact lens is cleaned with acetone. In the measuringchamber of the contact angle- measuring microscope a drop of distilledwater is placed on the surface of the contact lens. The developing dropis measured against the surface of the contact lens

Oxygen permeabilities (Dk values) are quoted in the unit "(cm³ O₂.cm²/cm².sec.mmHg)", oxygen transmissibilities in the unit"(mlO₂.cm/ml.sec.mmHg)".

Example 1: Heptakis-(2,6-di-O-n-pentyl)-β-cyclodextrin is prepared fromβ-cyclodextrin in a manner known per se (e.g. according to CarbohydrateResearch 214, 257 (1991)). That compound is refluxed for 4 days intetrahydrofuran with sodium hydride and 1-bromopent-4-ene undernitrogen. The reaction product,heptakis-(2,6-di-O-n-pentyl-3-O-(ω-pentenyl))-β-cyclodextrin, isobtained in a yield of 68% after working up and after columnchromatography in which silica gel Merck Si-60 and petroleumether/tert-butyl methyl ether (88:12 v/v) are used. The ¹ H-NMR datasupport the suggested configuration.

In the subsequent step, the 7 carbon-carbon double bonds perβ-cyclodextrin are crosslinked. For that purposeheptakis-(2,6-di-O-n-pentyl-3-O-(ω-pentenyl))-β-cyclodextrin with anequivalent amount of α,ω-dihydrogen-polydimethylsiloxane, degree ofpolymerisation =20, produced according to S. W. Kantor et al., J. Am.Chem. Soc. 76, 5190 (1954), is dissolved in a small amount of tolueneunder nitrogen. 1 . 10⁻⁴ mol percent ofcis-bis-(styrolo)dichloro-platinum, prepared in accordance with A.Albinati et al., Organo Metallics 6, 788 (1987) are added as catalyst.The solution is stable for 7 days at 20° C. To initiate thehydrosilylation reaction, the solution is poured onto a hot rotatingplate. At a temperature of 60° C. the reaction is complete after 2minutes. A colourless, transparent, rubbery film of the lipophilisedcyclodextrin/siloxane network is obtained. The film has a thickness offrom 50 to 200 μm and comprises up to 15% β-cyclodextrin.

Example 2: Hexakis-(2,6-di-O-n-pentyl)-α-cyclodextrin is prepared in amanner known per se from α-cyclodextrin. A mixture of that compound withsodium hydride in tetrahydrofuran and with a 1:5 mixture (mole/mole) of1-bromo-n-pent-4-ene and 1-bromo-n-pentane is heated under reflux for 4days. After working up and after column chromatography in which silicagel Merck Si-60 and petroleum ether/tert-butyl methyl ether (90:10 v/v)are used,hexakis-(2,6-di-O-n-pentyl)-3A-O-(ω-pentenyl)-3B,3C,3D,3E,3F-penta-O-n-pentyl-α-cyclodextrinis obtained as the main product in a yield of 74%. The ¹ H-NMR datasupport the suggested configuration.

For the hydrosilylation reaction, a linear statisticalco-(dimethylsiloxane)/(hydromethylsiloxane) polymer (PS 123.5, Petrarch)is used which comprises 9.8 mol % hydromethylsiloxane units (called"Sample 1" in the following Table). Analogously to Example 1, thesiloxane is reacted with the monofunctionalised α-cyclodextrin in thepresence of cis-bis(styrolo)dichloro-platinum as catalyst.

In a first experiment, 1 equivalent of Si--H groups of the siloxane istreated at 60° C. in toluene with 0.5 equivalent of C--C double bonds ofthe functionalised a-cyclodextrin. The product obtained from thatexperiment is called "Sample 2" in the following Table. In a secondexperiment, the compounds are used in a ratio of 1:1.1. The productobtained from that experiment is called "Sample 3" in the followingTable. The reactions are almost complete after 5 days. The reactionmixtures are washed with water. The products of the two experiments areisolated using preparative gel permeation chromatography (GPC) with aStyragel HPLC column and tetrahydrofuran. The composition of thecopolymers is ascertained by ¹ H-NMR spectroscopy. The integrals of thesignals at δ=4.67 ppm (CH₃ Si--H), at δ=0.49 ppm (CH₃ Si--(CH₂)--) andδ=0.06 ppm (CH₃ Si) are evaluated in order to ascertain the content ofunreacted hydromethylsiloxane units, units with bonded cyclodextrins anddimethylsiloxane units; see Table to this Example. The molecular weightof the polymers was measured by GPC in toluene for which a PDMScalibration (polydimethylsiloxane calibration) was used.

                  TABLE                                                           ______________________________________                                        to Example 2                                                                  Composition and molecular weight of the polymer Samples 1 to 3                Sample    K*     L*         M*   MW* (GPC)                                    ______________________________________                                        1         90%    9.8%       --   2336                                         2         90%    4.5%       5.4% 4850                                         3         90%    0.1%       9.6% 5872                                         ______________________________________                                         *K: content of dimethylsiloxane units,                                        *L: content of unreacted hydromethylsiloxane units                            *M: content of units with bonded cyclodextrins                                *MW: molecular weight, determined by GPC                                 

Example 3: A contact lens is produced as follows from the modifiedcyclodextrin obtainable in accordance with Example 1: The describedsolution, which is stable at 20° C. for 7 days, is introduced into ageometrically stable mould. The mould is closed and heated. The heatingcan be effected by heat radiation (infrared), in a water bath, or, inthe case of metal moulds, by induction. If the mould materials permit,the crosslinking can also be carried out under pressure.

At the temperatures indicated below the reaction is complete after thefollowing times:

    ______________________________________                                        Temperature (°C.)                                                                  30     40     50   60   80    100                                 Time (h)    48      6      1   0.5  0.25  0.1                                 ______________________________________                                    

Example 4: Analogously to. Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaIII with compounds of formula IV, the variables of formula III havingthe following meanings: n is 7, the two radicals R² are pentyl and R³ isallyl, and the variables of formula IV having the following meanings: R⁴and R⁵ are methyl, and x is the integer 5, 11, 17, 37, 41, 82 or 100.The following parameters are given below for the contact lenses producedin each case:

Value of the index x, ratio of Si--H bonds to C--C double bonds(referred to hereinafter as "SiH/CC"), proportion by weight of thecyclodextrin compounds of formula III (referred to hereinafter as "%CDX"), proportion by weight of the polydimethylsiloxane compound offormula IV (referred to hereinafter as "% PDMS"). Also, if determined,the contact angle, the Dk value and the Dk/L value are given.

a) x=5, SiH/CC=1.94, % CDX=47%, % PDMS=53%: contact angle 85°, Dk value200, Dk/L value 126.

b) x=5, SiH/CC=0.96, % CDX=64%, % PDMS=36%: contact angle 95°, Dk value78, Dk/L value 56.

c) x=11, SiH/CC=1.26, % CDX=38%, % PDMS=62%: contact angle 80°, Dk value163, Dk/L value 115.

d) x=17, SiH/CC=1.00, % CDX=33%, % PDMS=67%: contact angle 80°, Dk value236, Dk/L value 130.

e) x=37, SiH/CC=0.53, % CDX=32%, % PDMS=68%: contact angle 95°, Dk value326, Dk/L value 113.

f) x=41, SiH/CC=1.07, % CDX=17%, % PDMS=83%: contact angle 96°.

g) x=82, SiH/CC=1.02, % CDX=10%, % PDMS=90%: contact angle 97°.

h) x=100, SiH/CC=0.97,% CDX=9%, % PDMS=91%.

Example 5: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaIII with compounds of formula II, the variables of formula III havingthe meanings given in Example 4. There is used as compound of formula IIlinear statistical co-(phenylmethylsiloxane)/(hydromethylsiloxane)polymer 50:50, M_(n) =1146, (PS 129.5, Petrarch), which comprisesapproximately 50 mol % hydromethylsiloxane units. In the following thefurther parameters are given analogously to Example 4:

SiH/CC=1.05, % CDX=46%, % PDMS=54%: contact angle 94°.

Example 6: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaIII with compounds of formula II, the variables of formula III havingthe following meanings: n is 7, the two radicals R² are pentyl and R³ ispentenyl, and the variables of formula II having the following meanings:R⁶ is hydrogen, R⁴ is hydrogen or methyl and R⁵ is methyl and x is theinteger 5, 11, 17 or 37. In the following the further parameters for thecontact lenses produced in each case are given as in Example 4:

a) x=5, SiH/CC=1.01, % CDX=65%, % PDMS=35%: contact angle 90°, Dk value158, Dk/L value 116.

b) x=11, SiH/CC=1.29, % CDX=40%, % PDMS=60%: contact angle 87°.

c) x=17, SiH/CC=0.52, % CDX=50%, % PDMS=50%: Dk value 215, Dk/L value127.

d) x=17, SiH/CC=1.01, % CDX=34%, % PDMS=66%: contact angle 100°, Dkvalue 362, Dk/L value 143.

e) x=37, SiH/CC=0.55, % CDX=32%, % PDMS=68%: contact angle 100°, Dkvalue 476, Dk/L value 149.

f) x=37, SiH/CC=0.50, % CDX=35%, % PDMS=65%: Dk value 425, Dk/L value160.

Example 7: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaIII with compounds of formula II, the variables of formula III havingthe meanings given in Example 6. There is used as compound of formula IIlinear statistical co-(phenylmethylsiloxane)/(hydromethylsiloxane)polymer 50:50, M_(n) =1146, (PS 129.5, Petrarch), which comprises about50 mol % hydromethylsiloxane units. In the following the furtherparameters are given analogously to Example 4:

SiH/CC=1.05, % CDX=48%, % PDMS=52%.

Example 8: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaI with compounds of formula IV, the variables of formula I having thefollowing meanings: n is 7, the two radicals R¹ in positions 2 and 6 arepentyl, 40% of the radicals R¹ in position 3 are pentyl and 60% of theradicals R¹ in position 3 are pentenyl, and the variables of formula IVhaving the following meanings: R⁴ and R⁵ are methyl, and x is theinteger 5, 11, 17, 37, 82 or 100. In the following the furtherparameters for the contact lenses produced in each case are given as inExample 4:

a) x=5, SiH/CC=1.05, % CDX=75%, % PDMS=25%: contact angle 95°.

b) x=11, SiH/CC=1.27, % CDX=53%, % PDMS=47%: contact angle 79°.

c) x=17, SiH/CC=0.97, % CDX=47%, % PDMS=53%.

d) x=37, SiH/CC=0.91, % CDX=33%, % PDMS=67%.

e) x=82, SiH/CC=1.01, % CDX=17%, % PDMS=83%: contact angle 100°.

f) x=100, SiH/CC=0.99, % CDX=14%, % PDMS=86%: contact angle 100°.

Example 9: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaI with compounds of formula II, the variables of formula I having themeanings given in Example 8. There is used as compound of formula IIlinear statistical co-(phenylmethylsiloxane)/(hydromethylsiloxane)polymer 50:50, M_(n) =1146, (PS 129.5, Petrarch), which comprises about50 mol % hydromethylsiloxane units. In the following, the furtherparameters are given analogously to Example 4:

SiH/CC=2.11, % CDX=43%, % PDMS=57%: contact angle 90°.

Example 10: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaI with compounds of formula IV, the variables of formula I having thefollowing meanings: n is 7, two of the three radicals R¹ are pentenyland the remaining radicals R¹ are hydrogen, and the variables of formulaIV having the following meanings: R⁴ and R⁵ are methyl, and x is theinteger 2, 5, 11, 82 or 100. In the following the further parameters forthe contact lenses produced in each case are given as in Example 4:

a) x=2, SiH/CC=0.98, % CDX=69%, % PDMS=31%: Dk value 20, Dk/L value 30.

b) x=5, SiH/CC=1.28, % CDX=37%, % PDMS=63%: contact angle 93°.

c) x=11, SiH/CC=1.04, % CDX=25%, % PDMS=75%.

d) x=82, SiH/CC=1.05, % CDX=4%, % PDMS=96%: contact angle 96°.

e) x=100, SiH/CC=0.25, % CDX=14%, % PDMS=86%.

f) x=100, SiH/CC=0.59, % CDX=6%, % PDMS=94%.

Example 11: Analogously to Example 3, contact lenses are produced from acyclodextrin/siloxane network obtained by reacting compounds of formulaI with compounds of formula II, the variables of formula I having themeanings given in Example 10. There is used as compound of formula IIlinear statistical co-(phenylmethylsiloxane)/(hydromethylsiloxane)polymer 50:50, M_(n) =1146, (PS 129.5, Petrarch), which comprises about50 mol % hydromethylsiloxane units. In the following the furtherparameters are given analogously to Example 4:

SiH/CC=0.21, % CDX=65%, % PDMS=35%: contact angle 86°.

What is claimed is:
 1. A contact lens comprising a crosslinkedlipophilised cyclodextrin derivative which has repeating sub-units offormula V ##STR11## in which n is an integer from 6 to 15,the radicalsR¹ are each, independently of the others, hydrogen, R² or R⁷ wherein, ofthe (3 times n) radicals R¹, at least one radical R¹ has the meaning ofR⁷ and the remaining radicals R¹ are hydrogen or have the meaning of R²,R² being unsubstituted or halogen-substituted alkyl or alkyl-substitutedaryl and R⁷ being a hydrosilylizable moiety of the formula VI ##STR12##in which x is an integer from 1 to 10,000, and R⁴, R⁵, and R⁸ are each,independently of the others, hydrogen, alkyl, alkylene, phenyl, orhydroxy, with the proviso that at least two of the radicals R⁴, R⁵, andR⁸ in a moiety of formula VI are unsubstituted or halogen-substitutedalkylene or alkenylene,such that sub-unit of formula V and moiety offormula VI can be combined through hydrosilylation.
 2. A contact lensaccording to claim 1, comprising a crosslinked lipophilised cyclodextrinderivative which has repeating sub-units of formula V in whichn is aninteger of from 6 to 15, the radicals R¹ are each, independently of theothers, hydrogen, R² or R⁷ wherein, of the (3 times n) radicals R¹, atleast one radical R¹ has the meaning of R⁷ and the remaining radicals R¹are hydrogen or have the meaning of R², R² being unsubstituted alkyl andR⁷ being a di- or poly-valent moiety of formula VI in which x is aninteger of from 1 to 1000 and R⁴, R⁵ and R⁸ are each, independently ofthe others, hydrogen, alkyl, alkylene or phenyl, at least two of theradicals R⁴, R⁵ and R⁸ being alkylene.
 3. A contact lens according toclaim 1, comprising a crosslinked lipophilised cyclodextrin derivativewhich has repeating sub-units of formula V in whichn is an integer offrom 6 to 15, the radicals R¹ in the 2-position and in the 6-positionare unsubstituted alkyl, the radicals R¹ in the 3-position have themeaning of R⁷, x is an integer of from 1 to 1000 and R⁴, R⁵ and R⁸ areeach, independently of the others, hydrogen, alkyl, alkylene or phenyl,at least two of the radicals R⁴, R⁵ and R⁸ being alkylene.
 4. A contactlens according to claim 1, comprising a crosslinked lipophilisedcyclodextrin derivative which has repeating sub-units of formula V inwhichn is an integer of from 6 to 15, the radicals R¹ in the 2-positionand in the 6-position are unsubstituted alkyl, and at least 50% of theradicals R¹ in the 3-position have the meaning of R⁷ whilst theremaining percentage of the radicals R¹ in the 3-position areunsubstituted alkyl, x is an integer of from 1 to 1000 and R⁴, R⁵ and R⁸are each, independently of the others, hydrogen, alkyl, alkylene orphenyl, at least two of the radicals R⁴, R⁵ and R⁸ being alkylene.
 5. Acontact lens according to claim 1, comprising a crosslinked lipophilisedcyclodextrin derivative which has repeating sub-units of formula V inwhichn is an integer of from 6 to 15, the radicals R¹ in the 3-positionare hydrogen, the radicals R¹ in the 2-position and in the 6-positionhave the meaning of R⁷, x is an integer of from I to 1000 and R⁴, R⁵ andR⁸ are each, independently of the others, hydrogen, alkyl, alkylene orphenyl, at least two of the radicals R⁴, R⁵ and R⁸ being alkylene.
 6. Acontact lens according to claim 1, comprising a crosslinked lipophilisedcyclodextrin derivative which has repeating sub-units of formula V inwhichn is an integer of from 6 to 15, the radicals R¹ are each,independently of the others, hydrogen, R² or R⁷ wherein of the (3 timesn) radicals R¹, from 16.6% to 33.3% of all R¹ radicals have the meaningof R⁷ whilst the other radicals R¹ have the meaning of hydrogen or R²,R² being unsubstituted alkyl and R⁷ being a di- or poly-valent moiety offormula VI in which x is an integer of from 1 to 500 and R⁴, R⁵ and R⁸are each, independently of the others, hydrogen, alkyl, alkylene orphenyl, at least two of the radicals R⁴, R⁵ and R⁸ being alkylene.
 7. Acontact lens according to claim 1, comprising a crosslinked lipophilisedcyclodextrin derivative which has repeating sub-units of formula VII##STR13## in which n is an integer of from 6 to 15,R² is unsubstitutedalkyl, and R⁷ is a hydrosilylizable moiety of formula VIII ##STR14## inwhich x is an integer of from 1 to 500, R⁴ and R⁵ are each,independently of the other, alkyl or phenyl, and R⁸ is alkylene.
 8. Acontact lens according to claim 7, comprising a crosslinked lipophilisedcyclodextrin derivative which has repeating sub-units of formula VIIwhereinR⁷ is a divalent moiety of formula VIII, in which formulae n isan integer 6, 7 or 8, R² is lower alkyl having from 4 to 7 carbon atoms,x is an integer of from 1 to 200, R⁴ and R⁵ are each, independently ofthe other, lower alkyl or phenyl, and R⁸ is lower alkylene having from 3to 6 carbon atoms.
 9. A process,for the manufacture of a contact lensaccording to claim 1, which comprises processing in a manner known perse, to form a contact lens, a crosslinked lipophilised cyclodextrinderivative which has repeating sub-units of formula V ##STR15## in whichn is an integer of from 6 to 15,the radicals R¹ are each, independentlyof the others, hydrogen, R² or R⁷ wherein, of the (3 times n) radicalsR¹, at least one radical R¹ has the meaning of R⁷ and the remainingradicals R¹ are hydrogen or have the meaning of R², R² beingunsubstituted or halogen-substituted alkyl or alkyl-substituted aryl andR⁷ being a hydrosilylizable moiety of formula VI ##STR16## in which x isan integer of from 1 to 10 000, and R⁴, R⁵ and R⁸ are each,independently of the others, hydrogen, alkyl, unsubstituted orhalogen-substituted alkylene or alkenylene, phenyl or hydroxy, with theproviso that at least two of the radicals R⁴, R⁵ and R⁸ in a radical offormula VI are unsubstituted or halogen-substituted alkylene oralkenylene.
 10. A contact lens comprising a crosslinked lipophilisedcyclodextrin derivative which is obtainable by reacting a compound offormula I ##STR17## ##STR18## in which formulae n is an integer of from6 to 15,the radicals R¹ are each, independently of the others, hydrogen,R² or R³, wherein, of the (3 times n) radicals R¹, at least one radicalR¹ has the meaning of R³ and the remaining radicals R¹ are hydrogen orhave the meaning of R², R² being unsubstituted or halogen-substitutedalkyl or alkyl-substituted aryl and R³ being unsubstituted orhalogen-substituted alkenyl, x is an integer from 1 to 10,000, and R⁴,R⁵, and R⁶ are each, independently of the others, hydrogen, alkyl,phenyl or hydroxy, with the proviso that at least two of the radicalsR⁴, R⁵, and R⁶ in a compound of formula II are hydrogen,such thatsubunit of formula I and moiety of formula II can be combined throughhydrosilylation.
 11. A contact lens according to claim 1, comprising acrosslinked lipophilised cyclodextrin derivative which has repeatingsub-units of formula VII ##STR19## in which n is an integer from 6 to15,R² is an unsubstituted alkyl, and R⁷ is a hydrosilylizable moiety offormula VI ##STR20## in which x is an integer from 1 to 500, and theradicals R⁴, R⁵, and R⁸ are each, independently of the others, hydrogen,alkyl, alkylene, or phenyl, with the proviso that a minimum of two ofthe radicals R⁴, R⁵, and R⁸ are alkylene and a maximum of 25% of theradicals R⁴, R⁵, and R⁸ are hydrogen.